U.S. District Judge Rosemary M. Collyer said the Bureau of Alcohol, Tobacco, Firearms and Explosives properly limited its requirement to purchasers of two or more semi-automatic rifles greater than .22 caliber within five days in the states of California, Arizona, New Mexico or Texas.

The requirement was imposed after ATF acknowledged during congressional hearings it made mistakes in Operation Fast and Furious, a Phoenix-area investigation designed to catch weapons-trafficking kingpins. Agents lost track of many weapons they were trying to track to smuggling ringleaders, and some guns ended up at crime scenes in Mexico and the U.S.